Problem: If $a + b = -5$ and $x + y = 9$, what is $-5b - 2x - 2y - 5a$ ?
Solution: $= -5a - 5b - 2x - 2y$ $= (-5) \cdot (a + b) + (-2) \cdot (x + y)$ $= (-5) \cdot (-5) + (-2) \cdot (9)$ $= 25 - 18$ $= 7$